Batteries, including lithium ion batteries, lithium air batteries and lithium sulfur batteries, are well-known rechargeable means for storing electric energy. Lithium ion batteries comprise a cathode, an anode, a separator interposed between the cathode and the anode, and an electrolyte composition containing a solvent, a conductive salt and, often, one or more additives. The cathode and anode usually prepared by applying a composition comprising an active-electrode material, such as a cathode active material and an anode active material (depending on a final application of the electrode), a binder, a solvent, and optionally one or more additives, on a substrate, then drying, and compression-molding.
A nominal cell voltage currently adopted for lithium secondary battery, in particular lithium ion battery, is usually up to 3.7 V. This often corresponds to a charge cut-off voltage of 4.2 V. At the voltage higher than this point, the electrolyte system is often deteriorated because the components of the electrolyte system, such as a solvent, a conducting salt, and an additive, especially the additive material which is believed to form protective layer (often called “solid electrolyte interphase (SEI)”) on a surface of electrode(s) on initial charging, cannot endure such high voltage. However, the battery which can be operated at higher voltage (usually at 3.9 V or 4.1 V, or even up to 4.7 V) is desired in the art, and thus, developments of the electrolyte system suitable for the high-voltage batteries, and/or the component for such electrolyte system are required in the art. In terms of the charge cut-off voltage, such high-voltage batteries have charge cut-off voltage of higher than 4.2 V, in particular at least 4.25 V.
In addition, the technically-advantageous electrolyte system for batteries, especially for lithium-ion batteries, is demanded in the art in general.